Maths has a ton of fascinating quirks. For example, if you want to convert between miles and kilometres, you can use the Fibonacci sequence to make a conversion with a stunning degree of accuracy.

Quick: How many grams are in an ounce? How many euros is $1 worth? What's the square root of 65? Windows 10's search in the taskbar can answer these and similar questions.

Chromebook's browser-based operating system may be focused on the web, but its built-in app launcher has a few tricks up its sleeve -- including performing calculations and conversions without ever opening up a web page.

Chrome: You can easily convert just about anything with Google, but if you'd prefer a more automatic solution, AutoConvert is an extension that converts measurements mentioned on web pages on the fly.

I've long known that Google will convert between units if you type a query into the search engine (or your browser search bar), such as "50 miles kilometres". I hadn't realised that if you simply use an equals sign, Google will make an educated guess at the unit you're aiming for.

Android: Unit conversion apps are a bit of a bore, but Convert Everything takes the concept to a whole new level. It's probably the most complete unit conversion tool we've seen, and can convert everything from length measurements and currency to clothing/shoe sizes to resistance and magnetomotive force.

Chrome: DriveConverter expands on Google Drive's built-in file conversion tools to allow users to convert uploaded files to a larger variety of formats.

If you've ever wanted to convert an article to an ebook for later reading, it's usually a two or three step process. DotEPUB is a Chrome extension that handles the conversion in one simple click.

Windows: We've featured many ways to convert single PDFs to editable formats like a Word Doc, but if you work with PDFs regularly, you may need something a bit more robust. Shareware batch converter PDFZilla is free for the next few weeks.

iTunes can be notoriously slow at times, but—strangely—you can speed up your iTunes conversions by keeping the preferences window open.

Windows: Planes, trains and automobiles—a long trip in any of them calls for some portable video. Any Video Converter, a longstanding favourite Lifehacker tool, is still being updated and working strong, recently adding 1080p YouTube videos to its repertoire.

Windows only: If you need frequent access to word definitions and text translation, Lingoes is a portable application that does everything from dictionary word look-ups to translation of over 80 languages.

Linux only: Video downloading utility UTube Ripper saves a copy of your favourite YouTube videos for your offline viewing pleasure, even converting them into a non-flash format.

Windows only: We've covered a variety of tools for converting PDF files, but if you need to bulk convert a pile of them Zilla PDF to TXT Converter gets the job done quickly.

Windows only: If you're looking for a fire-and-forget video converter to help stock your iPod, iPodME is a dead simple and lightweight tool for bulk converting your video files. iPodME is a completely portable standalone application—a GUI wrapper of the venerable ffmpeg for the curious among you. Operation is as simple as running the application, dragging and dropping a list of video files you want to convert onto it, and adjusting the basic video settings. You can select the video dimensions and the quality using the plain English metric provided--slow, quality or turbo, size for instance—to determine the conversion speed. If you dig into the options menu you can also tweak the process priority. The default for the application is to take advantage of idle cycles and back off when you're actually attempting to do work. Using the fast, quality setting and leaving it on the default of idle, it took approximately one hour to convert 20 episodes of Fraggle Rock into iPod-compatible MP4 files. An unexpected bonus in such a small package is support for SRT subtitle files, if you have them for your favourite foreign media you can embed them as you convert. If you'd like more fine tuned control over your video conversions, check out the candidates in the Hive Five Best Media Converters and the Top 10 Free Video Rippers, Encoders, and Converters to fulfil your tweaking needs. iPodME

If you have a bunch of older Office documents to convert to the Office 2007 format and you want to do it quickly, tech blog Digital Inspiration offers an excellent tutorial on getting it done. No need to open and convert each individual file—instead, you can convert entire directories in bulk.

Windows only: Free application Xrecode converts your audio files from popular formats to any of the same formats. While it may not have the complexity and advanced features of previously mentioned MediaEncoder Audio Edition, it's also less complicated to use—just drag files you want to convert into Xrecode, choose the output format, and get started. Xrecode also sets itself apart with smart options for splitting audio by CUE files or by silence—perfect for quickly splitting large audio files, like your vinyl-to-MP3 conversion. Xrecode is freeware, Windows only.

Xrecode

We've previously pointed out ways to grab just the text from a PDF by emailing Adobe and using desktop apps, but having a web-based solution bookmarked could be pretty helpful as well. PDFTextOnline is a free, no-registration web app that quickly accepts files and pushes them to plain text, available for copying or saving as a .txt file. The added bonus is being able to change both the font and layout style of the exported text, along with access the bookmarks and properties from the original PDF. The web app claims to handle a number of foreign languages and fonts, so it might make for a good go-to-go solution if your PDF just won't open anywhere else.
PDFTextOnline

Windows only: Free application ASCGEN, or Ascii Generator dotNET, takes in standard pictures and puts out images generated entirely from simple computer text. While free web apps like ASCII-O-Matic do a decent job with small face portraits, ASCGEN can handle larger files and offers the same kind of brightness, contrast and level modifications as standard image editors—it just changes letters instead of pixels. Once you're done tweaking, you can output to picture, text or HTML files. ASCGEN is a free download for Windows systems only.
Ascii Generator dotNET